The case, announced Wednesday, will pit the might of Italy's largest broadcaster and its leading shareholder -- Prime Minister Silvio Berlusconi -- against Google in the same Rome circuit court where Berlusconi has himself faced multiple charges of corruption.

Mediaset lawyers said that, on a random visit in June, they found more than 325 hours and nearly 5,000 clips of Mediaset-owned content on YouTube.

"With the information that has come to light and the quantity of (Mediaset) files illegally on the site, it is possible to calculate that the group's three cannels have lost 315,672 audience viewing days," a company statement said.

Mediaset said the 500 million euros are in addition to additional damages not yet calculated based on lost advertising revenue.

The case comes on the heels of Monday's court-ordered closure of Colombo-BT.org, an Italian YouTube rival accused of the illegal sharing of music and movie files.